title: [Are clinical features derived from evidences and experiences outside of Japan applicable to clinical practices in Japan? Comparisons of results among studies conducted in US, Europe, Asian Countries and Japan].
abstract: Levetiracetam is an antiepileptic drug (AED) approved for the adjunctive treatment of partial seizures firstly in the US in 1999. In Japan, levetiracetam was approved for the adjunctive treatment of partial seizures. Accumulated evidences and experiences in US, Europe and Asian counties have indicated clinical features of levetiracetam (i.e., rapid onset of action, high efficacy and tolerability, no drug-drug interactions). One may ask whether the known clinical features are applicable to Japanese epilepsy patients with partial seizures. This article is aimed at answering such questions by reviewing published articles on effects of races onto pharmacokinetics and on efficacy and safety profiles shown in studies conducted in the US, Europe, Taiwan, China, Korea, Asian 6 countries and Japan, which allowed to compare the profiles across the different populations. Pharmacokinetic profiles were not different between Western and Japanese, and between Chinese and Western populations. The values of efficacy variables such as percentage (%) reduction of seizure frequency from baselines, 50% responder rate and seizure free rate at dose range of 1,000 mg-3,000 mg/d were similar across 4 open studies (Korea, 6 Asian countries, US, Europe and other western; % reduction: 43.2-52.3%, 50% responder rate: 43.6-57.9%, Seizure free rate: 16.2-20.2%). In the 6 placebo-controlled double blind studies (US, 2 Europe studies, China, Taiwan and Japan), the values of the efficacy variables of the levetiracetam arms (1,000 mg/d, 2,000 mg/d, 3,000 mg/d, 1,000-2,000 mg/d, 2,000-3,000 mg/d) were at least numerically superior to those of corresponding placebo arms even though the statistical significance was not obtained for all of the variables. The degrees of difference between the values of placebo and levetiracetam arms were within comparable ranges. These comparisons suggested levetiracetam would have similar efficacy and safety profiles in Japanese patients to those in the US, Europe, and the Asian countries, thereby indicating the known clinical features applicable to Japanese patients in usual clinical settings. In the open studies, average dosages were 1,335-1,953 mg/d. The interquartile ranges of the doses of the 6-Asian country study subjects showing 100% and 75- < 100% seizure reduction were 925-1,000 mg/d and 975-1,509 mg/d, respectively. The most frequent dose was 1,000 mg/d in the US open study. The % reduction and 50% responder rates at a dose of 1,000 mg/d in Japan study were superior to placebo with a statistical significance (% reduction: 19.6% vs 6.1%, 50% responder: 28.6 vs 13.8). These suggest 1,000 mg/d would be an efficacious dose for Japanese patients. In addition to the direct effects on seizures, these studies demonstrated that levetiracetam improved cognitive functions and quality of life of subjects.
authors.affiliation: Department of Neurosurgery, Asahikawa Medical University, Japan.
authors.forename: Kyousuke
authors.initials: K
authors.lastname: Kamada
mesh_terms: D000927:Anticonvulsants / Q000008:administration & dosage / Q000627:therapeutic use*; D002986:Clinical Trials as Topic; D004828:Epilepsies, Partial / Q000188:drug therapy; D005060:Europe; D005202:Asia, Eastern; D006801:Humans; D007564:Japan; D000077287:Levetiracetam; D010889:Piracetam / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D014481:United States
chemical_list: D000927:Anticonvulsants; D000077287:Levetiracetam; D010889:Piracetam